离子和带电粒子之间的相互作用受纳米,胶体颗粒表面上离子吸附控制,同时它决定着颗粒的微观性质、界面反应过程以及颗粒间相互作用。现有的离子界面反应理论没有考虑到离子特异性对离子.表面相互作用的影响。本研究建立了带电颗粒表面离子吸附模型。结果表明蒙脱石胶体表面离子吸附平衡存在着强烈的离子特异性效应。离子和表面之间的吸附能随离子浓度的增加而降低,随着粒子电荷密度(绝对值)升高而增加。根据建立的模型还可预测吸附反离子在扩散层中的位置,进而可计算出离子的吸附能与活化能。活化能直接决定了离子的吸附饱和度,且不同的离子遵循相同的规律。本研究表明建立的离子.表面相互作用模型在固,液界面反应中具有普适性的应用。
Ion exchange adsorption is an important physicochemical process at solid/liquid interfaces. In this study, an approach was established to estimate the activation energy of cation exchange reaction on the charged surface, considering Hofmeister effects. The experimental results showed that Hofmeister effects strongly affect the ionic adsorption equilibrium on the charged particle surface. The position of the adsorbed counterion in the diffuse layer was predicted according to the established model, and the ion exchange activation energies for different bivalent cations were estimated via the cation exchange experiments. The activation energy decreases with increasing ion concentration, and the adsorption saturation of cations is a function of the activation energy at different concentrations. The established model of cation exchange adsorption in the present study has universal applicability in solid/liquidinterface reactions.